1. Field of the Invention
The present invention relates to methods of extracting juice from fruit and to juice extraction presses and, more particularly, to a dual-cycle fruit juice extraction method and a pressing installation for the performance of such a method.
2. Description of the Prior Art
It is known in the art of fruit juice extraction to process fruit in two separate extraction cycles, whereby pure, natural fruit juice of first quality is obtained in a first extraction cycle involving a fruit mash pressing operation, and a juice of second quality is obtained in a second extraction cycle involving the addition of water to the concentrate or pomace which is left over at the end of the first pressing operation.
This kind of dual-cycle juice extraction method is widely used in the soft drink industry, because it is well suited to conformance with the regulatory requirements, according to which the pure fruit juice obtained in the first extraction cycle, if free of any additives, may be labeled and sold as "fruit juice", whereas the product obtained in the second extraction cycle is a soft drink base, or juice of second quality, which can be further processed to obtain either "nectar" or fruit-flavored soft drinks, the composition of which is likewise regulated.
In a known fruit juice extraction process, the soft drink base is obtained by using an elongated web filter, a so-called "extractor", onto which the pomace is deposited and repeatedly rinsed with water in a recirculating process, whereby the water receives a progressively higher concentration of the base substances with each rinsing cycle.
Juice fruit, such as apples, for example, contain 90-95% soluble substance, approximately 70% of which is removable from the apple mash in the first pressing cycle.
It has been found, however, that the second extraction cycle using a web filter, or extractor, has certain shortcomings and problems connected therewith:
The finally remaining pomace which cannot be processed any further has a high content of water and it may be necessary, under certain circumstances to subject it to a further pressing operation. The rinsing of the pomace and the subsequent pressing operation transfers a relatively large portion of turbidity causing substances to the juice, where they represent a detracting factor, whereas, if they remain in the pomace, they may actually be beneficial in the course of further processing of the latter.
Another shortcoming of the known second processing cycle for the extraction of second-quality juice from once-pressed pomace relates to the fact that this cycle involves a very costly and energy-intensive operation.